Mirror grinding machine



Jan. 29, 1957 F. T. GRISCAVAGE 2,779,137

MIRROR GRINDING MACHINE Filed Sept. 21, 1954 2 Sheets-Sheet l INVENTOR"Ill/11111115! ATTE IRNEYS a i Tm w 2 3 V JIM u 7M! 014; 5 cl a m 1 r CA 1, I I L; a m j a 1 W a m 1957 F. T. GRISCA'VAGE MIRROR GRINDINGMACHINE 2 Sheets-Sheet 2 Filed Sept. 21; 1954 INVENYOR. frank Igriscava' e ATTD RN EYS United States Patent-'0 MIRROR GRINDING MACHINEFrank Thomas Griscavage, Wilkes-Barre, Pa.

Application September 21, 1954, Serial No. 457,429

1 Claim. (Cl. 51-123) This invention relates to machines for grindingmirrors, lenses, and flat pieces of material in which discs for form ingmirrors and the like are oscillated over tools with an abrasive or othergrinding or polishing substance positioned between the tools and discswhereby surfaces are finished to millionths of an inch precision.

The purpose of this invention is to provide means for oscillating discsin relation to tools or tools in relation to discs whereby mirrors,lenses, and the like are adapted to be accurately finished and polished.

In the conventional method of grinding mirrors and large opticalelements by hand, the grinding operation includes rubbing one glass discon top of another with abrasives and water between the discs, the upperdisc being moved back and forth over the tool and rotated to the leftwith the result that the same spot on a disc never comes in contact witha similar spot on the tool and by this means the upper disc is providedwith a concave surface with the lower tool having a convex surface. Bythis method an extremely even grind and polish is obtained, the surfacesbeing precision finished and being accurate by a millionth of an inch.

With this thought in mind, this invention contemplates a mechanicaldevice for oscillating discs over tools or tools over discs, such asmirrors, lenses, and flats whereby accurate grinding and polishing isaccomplished and wherein the elements may readily be removed for addingabrasive and the like, and replaced. p

The object of this invention is, therefore, to provide means formounting and operating a reciprocating frame with offset pushers thereinwhereby with the tools or discs positioned in openings in the framediscs or tools are caused to rotate and slide over correspondingelements with the moving elements continuing to rotate in the samedirection.

Another object of the invention is to provide a machine for grinding andpolishing optical elements in which parts are oscillated overcorresponding parts in which the upper parts are adapted to be removedfor adding abrasive and the like between the elements, and replaced.

Another object of the invention is to provide a reciprocating frame withoifset elements positioned in pockets therein for oscillating elementsin the pockets over tools, discs, and the like in which means isprovided for controlling the length and speed of the reciprocatingstrokes.

A further object of the invention is to provide a machine for accuratelygrinding and polishing optical elements in which the machine is of asimple and economical construction.

With these and other objects and advantages in view, the inventionembodies a plurality of turntables rotatably mounted in a frame withtools positioned on the turntables and discs freely slidable n thetools, a frame having pockets therein in which the discs are positionedand having offset disc-engaging elements in the pockets and an operatingtransmission for reciprocating the frame and rotating the turntables.

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Other features and advantages of the invention will appear from thefollowing description taken in connection with the drawings, wherein:

Figure 1 is a plan view illustrating a typical arrangement of themachine.

Figure 2 is a typical longitudinal section through the machineillustrating the reciprocating and rotating elements, the discs andtools being shown concave and convex, as finished.

Figure 3 is a plan view of one corner of the reciprocating frame withthe parts shown on an enlarged scale andillustrating the oscillatingpath through which a disc positioned on a tool travels.

Figure 4 is a cross section through one side of the reciprocating framebeing taken on line 4-4 of Figure 1 illustrating the arrangement of therails and tracks and with the parts shown on an enlarged scale.

Figure 5 is a cross section taken on line 5-5 of Figure 3 illustratingthe free mounting of the filler partitions in the frame.

Figure 6 is a detail illustrating the mounting of one of the disc-movingelements or pushers.

Figure 7 is a plan view illustrating a modification wherein a tool ismounted to slide or oscillate over a mirror.

Figure 8 is a detail illustrating a typical method of applying a weightto a tool or mirror.

Referring now to the drawings, wherein like reference characters denotecorresponding parts, the improved mirror grinding machine of thisinvention includes a frame having a base 10 with a tray 11 supported byuprights 12, turntables 13 on the upper ends of shafts 14 rotatablymounted in bearings 15 in the tray 11, a belt 16 trained over pulleys 17on the lower ends of the shafts 14, a reciprocating frame having sidebars 18 and 19 connected with end bars 20 and 21, a filler including acenter partition 22 with transversely disposed partitions 23 and 24providing pockets in the frame, actuating rollers 25 carried by thetransversely disposed partitions, similar rollers 26 carried by the endbars 20 and 21, bumpers 27 carried by the side bars 18 and 19, bumpers28 carried by the center partition 22, the rollers and bumpers of theindividual pockets being diametrically opposed, and suitabletransmission elements for reciprocating the frame and rotating theturntables including a pitman 29 adjustably mounted by a bracket 30 on apulley 31, a gear housing 32, a reduction gear 33, a motor 34, andsuitable mounting and connecting elements.

As illustrated in Figure 1, the motor 34 drives the reduction gear 33through a belt 35 which is trained over a pulley 36 on the motor shaftand a pulley 37 on a reduction gear shaft 38. The gear housing 32 isactuated by the reduction gear unit 33 with a shaft 39 and the pulley ordrum 31 is carried by a shaft 40 that is extended from the housing 32.

The bracket 30, which is shown particularly in Figure 2, is providedwith an elongated slot 41 through which a bolt 42 that clamps thebracket on the drum or pulley 31 extends.

The pitman 29 is connected to the bracket 30, at one end, with a balland socket joint 43 on the end of an arm 44 and the opposite end isconnected to the end bar 21 of the reciprocating frame with a ball andsocket joint, as indicated by the numeral 45.

The belt 16, for rotating the turntables, is driven from the drum 31with a belt 46 trained over the drum and also over a pulley 47 on ashaft 48 rotatably mounted in bearings 49 and 50 and provided with aworm 51 that meshes with a worm gear 52 on a shaft 53 on which a pulley54, over which the belt 16 is trained, is mounted. The shaft 53 isrotatably mounted in a bearing stand 55 which Patented Jan. 29, 1957 issecured to the base 10 ofthe housing or frame with bolts 56 which extendthrough a base 57 of the stand.

The belt 16 is trained over an idler pulley 58 on a bearing stand 59 andalso over the pulleys 17 on the shafts 14, the pulleys 17 being retainedon lower ends of the shafts 14 with nuts 60 and Washers 61.

By this means, the horizontally disposed frame is reciprocated and theturntables are rotated slowly and, as illustrated in Figure 3,reciprocation of the frame moves the discs over the tools withoscillating movements whereby the discs are moving continuously andregistering points of the discs and tools never return to the samepositions.

The discs are actuated by the rollers 25 and 26 and with the parts, asillustrated in Figure 3, longitudinal movement of theframe causes theroller 25 to engage a disc, such as disc 62 with the disc moving overatool 63' and engaging the bumper 28. With continuous movement of theparts, the disc 62 moves to the position indicated by broken line 64 andwith return movement of the frame the roller 26 urges the disc againstthe bumper 27 whereby the disc is returned to a starting position inregistering relation with the tool 63.

The rollers 25 and 26 are carried on arms 65 of brackets 66, thebrackets being secured by bolts 67 and nuts 68 to angularly disposedsections 69 of clips 70, the base sections of the clips being secured tothe transversely disposed partitions 23 and 24 of the filler with bolts71 and nuts 72.

The ends of the center partition 22 and transversely disposed partitions23 and 24 of the filler f the reciprocating frame are freely held inU-shaped brackets 73 with projections 74 of the partitions extendedthrough notches 75 in the brackets with notches 76 in the partitionsbeing positioned in the notches 75. The ends of the brackets 73 areprovided with flanges 77 and 78 that are secured to the side and endbars with bolts 79 and nuts 80.

The bumpers 27 and 28 are secured to the bars and partitions withsuitable bolts or screws, as indicated by the'numeral 81.

The side bars 18 and 19 of the reciprocating frame are provided withrails 82 having extended flanges 83, the flanges being positioned toslide between spaced flanges 84 and 85 of tracks formed with angle irons86 and 37, the angle irons being secured to the uprights or posts 12 ofthe mounting frame, such as by welding, as shown in Figure 4.

The tray 11 is formed with inclined side and end Walls, as indicated bythe numeral 88, with filling elements 89 connecting the Walls and trayto end rails formed with angle irons 90 and 91 and to similar side rails92 and 93. The tray is provided with a drain 94 that is adapted to carryaway excess fluid used in grinding the elements.

In the design illustrated in Figure 7, a mirror 95 is positioned upon asuitable turntable and a tool 98 ac tuated over the mirror with anoscillating movement by rollers 99 and 100 on brackets 101 and 102 in areciprocating frame 103. The brackets 101 and 102 are similar to thebrackets 66 and clips 70 and the frame 103 is also provided withbumpers, as indicated by the numerals 104 and 105.

The frame 103 is slidably mounted in rails 106 and 107 and the rail 106is adjustably mounted by extensions 108 4 and 109 in which elongatedslots 110 and 111 are provided, respectively. The rail is secured inadjusted positions with bolts 112. p

The frame 103 is adapted to be reciprocated by a pitman 113, similar tothe pitman 29, the pitman being connected to the frame 103 with a balland socket joint 114.

In the detail illustrated in Figure 8, a mirror 115 is provided with acover 116 and a layer of material, such as lead as indicated by thenumeral 117, may be positioned between the mirror and cover to provideweight to facilitate grinding the lower surface of the mirror with themirror positioned on a tool such as one of the tools shown in Figure 2.

In starting the grinding and polishing operation all tools and discs areflat on both sides, and mirrors six inches in diameter or smaller mustbe provided with weights. With continued operation of the machine theupper surfaces of the tools are ground and polished to provide convexsurfaces and the meeting surfaces of the discs are ground and polishedto provide concave surfaces as shown in Figure 2.

With the assembly of parts, particularly as illustrated in Figure 7, asingle tool is illustrated as being actuated with an oscillatingmovement over a mirror or lens, and it will be understood that insteadof the single tool shown in Figure 7, a plurality of tools arranged in aframe forming a battery, as illustrated in Figure 1, may be used and thetools may be assembled in different designs and actuated with anoscillating movement independently or as a complete unit.

The transmission, including the gear reduction 33 and gear housing 32,makes it possible to actuate the discs and rotate the tools atrelatively slow speed.

It will be understood that other modifications, within the scope of theappended claims, may be made in the design and arrangement of the partswithout departing from the spirit of the invention.-

What is claimed is':

A mirror grinding and polishing machine comprising a turntable, meansfor rotating the turntable, a tool mounted on the turntable, a discpositioned on the tool, a frame having a pocket therein positionedaround the disc, side walls of the pocket being spaced from theperiphery of the disc, diametrically opposed rollers mounted on theframe positioned in the pocket and adapted to contact the peripheralsurface of the disc, diametrically opposed bumpers also mounted on theframe, positioned in the pocket and adapted to contact the" peripheralsurface of the disc, and means for actuating the" frame with anoscillating movement.

References Cited in the file of this patent UNITED STATES PATENTS1,485,321 Wilkinson Feb. 26, 1924 1,639,012 Tillyer' Aug. 16, 19271,972,086 Buckley Sept. 4, 1934 2,246,869 Troendly et al. June 24, 19412,398,628 Dykoski Apr. 16, 1946 2,404,282 Fr'uth' July 16, 1946 FOREIGNPATENTS 804,761 Germany Apr. 30, 1951

